Apparatus for driving rotary electric switches



Feb. 11, 1969 G. JANOSKA 3,

APPARATUS FOR DRIVING ROTARY ELECTRIC SWITCHES Filed July 11, 1966 Sheetof 5 Feb. 11, 1969 Filed July 11, 1966 G. JANOSKA 3,427,411

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APPARATUS FOR DRIVING ROTARY ELECTRIC SWITCHES I Filed July 11, lessSheet 4 or 5 G- JANOSKA Feb. 11, 1969 I APPARATUS FOR DRIVING ROTARYELECTRIC SWITCHES Filed July 11, 1966 Sheet United States Patent3,427,411 APPARATUS FOR DRIVING ROTARY ELECTRIC SWITCHES GeorgesJanoska, Courbevoie, France, assignor to Societe a ResponsabiliteLimitee: Societe Lamy dEtudes et de Recherches Soler, Courbevoie,Hauts-de-Seine, France, a corporation of France Filed July 11, 1966,Ser. No. 564,219 'Claims priority, application Switzerland, July 12,1965,

9,723/ 65 US. Cl. 20038 6 Claims Int. Cl. H01h 3/32 ABSTRACT OF THEDISCLOSURE The invention relates to a programmed sequential switchingdevice.

It refers more particularly to a sequential switching device comprisinga plurality of rotary switches, wherein the successive switching statesare determined by a programme established on the basis of scanning andtiming parameters.

In know device the scanning parameters of the switching programmerepresent the selection of the address or destination corresponding toeach input and/or output pole, which forms the stored space divisionswitching programme. The time division switching programme is the rhythmat which are driven the said switches scanning the input and/ or theoutput poles.

In these known devices, one of the switches, being at a given moment ina position n, will next occupy either the position n+1 or the positionn- 1, so that these devices are incapable of effecting varied programmescomprising a large number of switching states or comprising a variablesuccession.

The present invention seeks to make it possible to programme, in anysuccession, the sequence of states of a switching device.

Another object of the invention is to make the timing parameters and thescanning parameters of the switching devices independent of each otherand therefore separately programmable.

A further object of the invention is to provide means for introducingand storing the timing and scanning parameters in the switching device.

The invention has the further aim of permitting the construction ofswitching devices capable of being driven mechanically, with highpositional accuracy, in accordance with programmes comprising stoppingand driving phases whose magnitude and duration may be varied.

This invention provides a sequential switching device capable ofmemorising and operating according to a programme, the device comprisinga plurality of rotary switches connected to a common motive power inputby kinematic chains comprising uniform motion drive means andintermittent drive means at least one of the switches having contactsfor electrical connection to corresponding external signal sources andbeing capable according to the said programme of alternately moving toact as a Patented Feb. 11, 1969 scanning switch for scanning the signalsfrom the said sources and remaining at rest in connection with one ofthe contacts; in which device each scanning switch is connected inseries with a timing switch arranged to close the circuit through thescanning switch during at least part of the time the scanning switch isat rest and of maintaining the said circuit open while the scanningswitch is movng, each scanning switch when moving from one rest positionto the next rest postion passing over a programmed whole number ofcontacts, the number being determined by the kinematic chains connectingthe scanning switch to the motive power input; the scanning switch beingdriven via the drive to the timing switch whereby the operation of thescanning switch is always dependent upon the operation of the timingswitch.

When the device comprises two scanning switches and a common timingswitch, the two scanning switches are successively and alternatelydriven and stopped, being electrically inhibited while being driven andelectrically activated when stopped, one of the switches being activatedwhile the other is stopped, and vice versa; the two scanning switchescan thus feed a same set of external circuits (addresses) according totwo different intermittent drive programmes and to two programmes ofswitching on and off the circuits controlled by the common timingswitch.

The device may comprise a further rotary switch provided with brusheswhich are not identically spaced and which are separated always by awhole number of contact studs, the said further switch being connectedin series in the circuit connecting the timing switch and the scanningswitch, this further switch and the Scanning switch being both drivenfrom the timing switch which closes the circuits when the two switchesare at rest, the said scanning switch likewise having a plurality ofbrushes separated one from another, by a whole number of contact studs,the path of the scanning switch being divided in such manner that ineach of their rest or switch positions the brushes of the scanningswitch designate corresponding circuits which are independent of oneanother. In such an arrangement, the circuits closed by the brushesrepresent the Boolean product of the two sets of circuits.

In the device of the invention the intermittent driving programme ofeach scanning switch may be controlled by the timing switch in such amanner that between two successive active switching positions thescanning switch passes over a whole number of contact, the number beingdetermined by the driving programme and being always greater than one;the scanning switch being stopped during the execution of the programmeat least once at each of its switching positions.

The aforesaid intermittent drive means may comprise a looped delay linein which every second element stores one term of the programme, allowingvariation of the intermittent drive programme.

When a plurality of switches is driven by a single kinematic chain inaccordance with a common intermittent drive programme, each switch mayhave a number of contacts, and therefore of possible rest positions,different from that of the other switches of the kinematic chain.

The invention is described in greater detail below with reference to theaccompanying drawings, in which:

FIGURE 1 illustrates diagrammatically a switching device which can beused for the reception and transmission of signals;

FIGURE 2 illustrates in profile the kinematic driving chains of theswitches of the arrangement illustrated in FIGURE 1;

FIGURE 3 represents in Cartesian coordinates the movements of theelements of said device;

FIGURE 4 illustrates an alternative form of the device;

FIGURE 5 represents in cartesian co-ordinates the movements of theprincipal elements of the device illustrated in FIGURE 4;

FIGURE 6 illustrates in elevation the components of a delay line;

FIGURE 7 illustrates in plan an arrangement for controlling fourswitches according of a variable programme;

FIGURE 8 illustrates the arrangement of FIGURE 7 in elevation;

FIGURE 9 shows the electric diagram of the arrangement of FIGURE 7;

FIGURES 10 and 11 are diagrams of the operation of the arrangement ofFIGURE 7.

The switching device illustrated in FIGURE 1 comprises two scanningswitches 1 and 2, a timing switch 9, input circuits 101 to 108, anoutput circuit 200, and internal circuits 201 and 202.

This device, which is mentioned solely by way of example, is capable ofscanning the input circuits 101 to 108 in accordance with apredetermined programme. The number of circuits illustrated is obviouslynot a limitation; the scanning switches 1 and 2 may, alternatively, beprovided with further contact studs, which may be designated 11, 12, 13and 21, 22, 23 extending along their entire circumferences.

In the position illustrated in FIGURE 1, the active circuit is thecircuit which connects the input channel 104 to the output channel 200,passing through the stud 14 of the switch 1, the brush 19, the channel201 of the internal circuit, the semicircular contact 31 of the switch9, and the brush 39 of the latter.

The device may be so associated with external apparatus that the inputchannel 104 is connected to a signal source and a signal receivingdevice is connected to the output channel 200.

The brush 39 of the timing switch 9 is rotated continuously so that,during one half of each revolution the output channel 200 is connectedto the brush of one scanning switch while, during the other halfrevolution, the output channel is connected to the brush of the otherscanning switch. The brushes 19 and 29, of the scanning switches are sodriven, intermittently and in co-operation with the brush 39 of thetiming switch 9, that the brush of one scanning switch moves only whenthe output channel 200 is connected to the brush of the other scanningswitch. All the switches are driven according to the aforementionedpredeterminde programme.

Thus, for each half revolution of the timing switch, one scanning switchis stopped and activated (connected, or on) and the other exploringswitch is rotating and inhibited (disconnected, or off).

As long as a scanning switch 1 or 2 is disconnected, it can pass overany number of studs, to reach the next switching position, according toits driving programme. Thus, the space division switching programme,that is to say the sequence in which active switching positions arereached (which sequence is determined by the intermittent drivingprogramme), is independent of the rate at which the exploration iscarried out and the duration of each connection between the input andoutput circuits (which factors are determined by the time divisionswitching' programme).

When signals to be selected by the scanning operation are separated intime by periods sufiicient to allow the scanning brush to berepositioned between the occurance of two successive signals, a singlescanning switch may be used.

FIGURE 2 illustrates the kinematic chains driving the switches 1, 2 and9.

The shaft 9a of the timing switch brush 39 is driven by a chain ofelements 500, 519, 519, 509, which kinematic chain comprises the meansof executing the time division switching programme.

The shaft 1a of the scanning switch 1 is driven by the elements 509,511-511, and 501, and the shaft 2a of the scanning switch 2 is driven bythe elements 509, 512- 512', and 502. These two kinematic chainsrepresent the component elements of the space division switchingprogramme.

In the example illustrated, element 500 is a driving pinion keyed on thedriving shaft of the device, which is driven, for example, by asynchronous motor.

This driving pinion is provided with three cylindrical stop surfaces506, 507, and 508, and with three starting teeth 503, 504, and 505, eachtooth having associated therewith an adjacent recess. In this examplethe pinion 500 may be considered to have twenty-four circumferentialdivisions and the three starting teeth are so distributed that there aresix circumferential divisions between the tooth 503 and the tooth 504,ten divisions between the tooth 504 and the tooth 505, and eightdivisions between the latter and the tooth 503.

A driven pinion 519 has twelve circumferential divisions, over whichthree teeth 529 are distributed which are spaced apart by fourcircumferential divisions, that is to say situated at in relation to oneanother, and their stopping positions correspond to zero, four, andeight divisions.

In a second plane the driving pinion 500 has teeth distributedcontinuously around its circumference, as indicated at 500, co-operatingwith corresponding teeth '519' on the pinion 519 and situated in thesame plane as the tooth 500'. The teeth 519' are removed at pointscorresponding to the stopping positions of the pinion 519.

One cycle of the movement of the pinion 519 is defined as the movementcorresponding to one rotation of the pinion 500; which rotationcomprises the twenty-four circumferential divisions of the drivingpinion 500-.

The diagram 519 in FIGURE -3 illustrates graphically the intermittentmovement of this pinion 519, the absissa representing rotation of thepinion 500 and the ordinate rotation of the pinion 519, both in theirrespective circumferential divisions. In this example, a cycle of thepinion 519 comprises three equal uniform movements and three motionlessintervals, each movement comprising four divisions but the motionlessintervals being of different durations, comprising in succession '2, 6and 4 divisions of the reference pinion 500.

An element 519", toothed over its entire periphery, is solid with thepinion 519 and meshes continuously with a pinion 509 keyed on the shaft9a of the timing switch 9, the numbers of teeth of the pinion 509 and ofthe element 519 being in the ratio of 2/ 3.

The driving programme of the timing switch is illustrated at 509 in'FIGURE 3. A single programme cycle comprises forty-eightcircumferential divisions of the reference pinion 500; each movementcovers an angle of 1r radians.

The scanning switch 1 is driven via a pinion 501, secured to the brushshaft In, its cycle comprising stopped and driven phases, as shown at501 in FIGURE 3; the parts of the horizontal lines shown heavycorrespond to the times during which the scanning switch 1 is stationaryand its bruch 19 is connected to the output channel 200; that is thetimes when the switch is activated. These activated periods constitutethe time division switching programme of the said switch.

Similarly, the scanning switch 2, which is driven by a pinion 502, inFIGURE 2, whose topped and driven phases are shown at 502 in FIGURE 3,is activated during periods only complementary to the activated periodsof the switch 501. These complementary activated periods correspond topart of the times during which the corresponding exploring switch isstopped. The pinion meshes with a pinion 511' in the ratio 17 to 12. Theswitch 1 comprises seventeen contact studs uniformly spaced apart, ofwhich only seven are shown in FIGURE 1.

The pinion 511' is fixedly connected to a pinion 511 and receivestherefrom an intermittent movement which is imparted to the pinion 511,via three teeth 521 cooperating with a. single starting tooth 520 of apinion 509', on each revolution of the pinion 509'.

The sequential space division switching programme of the switch '1 willthus be a sequence of 17 X3=51 terms which in order are:

0, 2, 8, 12, 14, 3, 7, 9, 15, 2, 4, 10, 14, 16, 5, 9, 11, 0, 4, 6, 12,16, l, 7, 11, 13, '2, 6, 8, 14, 1, 3, 9, 13, 15, 4, 8, 10, 1'6, 3, 5,ll, 15, 0, 6, '10, 1 2, l, 5, 7, 13, 0.

The pinion 502 is keyed on the shaft 2a of the scanning switch 2 andmeshes with a pinion 512' in the'ratio 211 to 12.

The scanning switch 2 has twenty-one uniformly spaced contact studs.

The pinion 512' is fixedly connected to a pinion 512 and receivestherefrom an intermittent movement, the pinion 512 being driven by fourteeth 542, from the starting tooth 520 of the pinion 509'. Between eachof their stopped positions the pinions 511 and 512 are drive by uniformmotion pinions, not illustrated in FIGURE 2.

The sequential space division switching programme of the scanning switch2 is a sequence of 2l1 2=42 terms, the intermittent driving programme ofsaid switch 2 being composed of two terms, namely two and fourdivisions.

In this example, the product 42x51 yields 2142 states which representthe complete space division switching programme of the two scanningswitches 1 and 2. The complete switching programme of the device isprovided by the superimposition of the time and space division switchingprogrammes.

FIGURE 4 illustrates a device in which the scanning switches areconnected to the lines and to the columns of a conventional switchingmatrix 110. The switches 1 and 2 in FIGURE 4 scan the lines, andswitches t3 and 4 scan the columns of the matrix 110, this part of thedevice being illustrated generally, and only the associated timingswitch 9 and its circuits being shown in greater detail.\

Table I below indicates the scanning switches which are activated independence on the positions of the timing switch brushes, thesepositions being repeated twice per revolution.

TABLE I Position Scanning of timing switch switch 9 activated Thescanning switch 1 is connected to the contact 91 of the timing switch 9;the scanning switch 2 is connected to the contact 92; the scanningswitch 3 to the two contacts 93 and 93'; and the switch 4 to the contact94.

This arrangement is particularly advantageous for reasons ofreliability, because in operation only one scanning switch is moving atone time.

FIGURE 5 illustrates the operation of the device of FIGURE 4. Theperiods during which each scanning switch is activated by the timingswitch 9 are indicated by heavy horizontal lines for the correspondingdiagrams 1,2,3, and 4 in FIGURE 5.

In order to enable programming the driving of the scanning switches andtiming switch respectively, the intermittent driving kinematic chainsproviding a constant stored programme are substituted in the deviceill-ustrated in FIGURE 4 and just described by mechanical delay lines,such as those described in US. Patent No. 2,978,919. One of the elementsof each delay line is fixedly connected to the corresponding switch, sothat the delay line can drive the switch according to a programmerecorded in the line. After registration of a programme, each delay lineis looped on itself during operation, which permits repetition of therecorded programme until a new programme is introduced.

Each of the scanning switches 1, 2, 3 and 4, which receives its drivefrom the corresponding delay line, may at any moment be in one of thefour operational modes illustrated in the corresponding one of thediagrams 1, 2, 3 and 4.

The delay line driving the timing switch 9 receives its drive directfrom an input driving shaft constituting the common source of motivepower. Each of the delay lines driving the scanning switches 1, 2, 3 and4 is started from the drive of the timing switch 9. FIGURE 5 illustratesthe different resulting movement of the scanning switch driving pinionsidentified in FIGURE 5 by 501,

502, 533, and 534.

FIGURE 6 illustrates in elevation the elements constituting a delay lineconstructed in accordance with the prior patent specification referredto above, in which the shafts carrying the pinions 501 and 501' arestarted by the timing switch 9 when the latter passes through position4, as shown by the diagram in FIGURE 5.

The delay line comprises a first series of elements 522, 523 each ofwhich memorises a term of the driving programme, and a second serieswhich comprises similar elements and which is offset by half a row inorder to co-operate with two neighbouring elements of the first series,the second series 512, 513, 514 being then empty. In the course of afirst part of the driving of the delay line, each element of the firstseries transmits a term of the programme to an element of the secondseries, for example the element 522 to the element 513, the element 523to the element 514, and so on.

In the course of a second part of the driving of the delay line, eachelement of the second series returns the term, which it had stored, toan element of the first series (which will hereinafter be referred to asthe main series) but with offsetting by one row.

FIGURES 7 and 8 illustrate another example of the switching device,comprising four switches A, B, C, D, which can constitute a programmer.FIGURE 9 shows the electric diagram of this arrangement.

In this arrangement, the timing switch D is fixedly connected to adriving shaft 43 and is connected to serve as a rotary contact breaker,as shown by the diagram in FIGURE 10, during rotation of the switches A,B, C, to ensure that the signals transmitted will always coincide with adefined state of the switching positions. The time division switchingprogramme comprises two alternating terms (the admission of thecurrent), one of a duration of 91 of a revolution of the driving shaft43 and the other of of a revolution of the said shaft.

The driving shaft 43 is also fixedly connected to a pinion 44, arrangedto drive the intermittent gears. The pinion 44 controls the pinions 45and 46 alternately as indicated by the diagrams in FIGURE 11.

The driven pinion 45, arranged for a programme, having a single term,advances, for each revolution of the pinion 44, by half a revolutioncorresponding to two switching positions of the switches B and C, whichare driven by the pinion 45 in different ratios. The switch B in facthas three switching positions and its driving ratio is therefore /1,while the switch C has five switching positions and is driven in theratio 5/4.

The driven pinion 46 is arranged for a programme comprising two terms,the first corresponding to the driving of the exploring switch 1,comprising four switching positions, and the second to a three-posiitondrive. The output signals are transmitted by the scanning switch Ahaving four poles and by the scanning switch B having three poles. Thus3 4=12 different output signals are obtained which are established asfollows:

TABLE II Reference Circuits established byletter for signal A and B I lalb K 1a 3b L 2a 1b R 3a 3b S 4a lb U 4a 3b If it is assumed that theswitch C is short-circuited, the switching programme would in this casebe reduced to the emission of 4 12=48 signals, that is one of thesignals in each rest position. This is equivalent to exploring aconventional matrix in four different ways.

However, the switch C permits the programme of the device to be varied.It can interrupt the circuits in accordance with its own programme. Thisprogramme is modified by means of the contactors E and F (FIGURE 9)which have three positions and are controlled manually.

It is thus possible to choose from nine switching programmes, which canbe established as follows:

TABLE III Selection of programmes by Circuits established contractors Eand F for B through 0 Programmes E on 3c-F on 60.

Because of the driving of the switch A, which alternates in relation tothe switches B and C, the switching sequence of the switch A providesfor the emission of sixteen signals.

The switching sequence of the switch B provides for the emission of sixsignals, and the switching sequence of the switch C of ten signals.

The smallest whole common multiple of 16, 6 and 10 is 240. Eachprogramme can therefore be composed of 240 terms.

Table IV below shows: in the first column, the serial number of thesignals emitted; in the next three columns the switching positions ofthe switches A, B and C and in the next nine columns the performance ofthe nine programmes.

In the three columns indicating the positions of the switches, theactual sequences of the switches are demarcated by horizontal lines.

It may be observed that these limits coincide: every thirty switchingpositions for the switches B and C (the smallest common integralmultiple of 6 and 10) every forty-eight switching positions for theswitches A and B (the smallest integral common multiple of 16 and 6)every eighty switching positions for the switches A and C (the smallestintegral common multiple of 16 and 10) and only after two hundred andforty switching positions for the switches A, B and C.

TABLE IV Position of Signals transmitted in dependence on programmeswitches r At A B C P1 P2 P3 P4 P P0 P7 Ps Pr 0 1-...- 141 lb 2 la 3b 3c3-.-..3a 3b 3c 4....-30. 2b 5c 5- 2a 2b 5c 6.--.- 211 lb 20 L 10 7.....4a lb 20 S 8---.-411 3b 40 U 9--...- 3a 3b 46 R 10....3a 2b 10 P P P P PP P P P 11---.1a 2b 10 J .l' I J J J J I .T 12-..- 1a 1b 3c I I I13-.--441 1b 3c 14---. 4a 3b 5c 15--.. 2a 3b 5c 16-... 2a 2b 20 2b 2c .TJ I 18...-1a 1b 4c I I I 1b 4c O O O 3b1cRRRRRRRRR SblcNNNNNNNNN 2!) M M2!) T T 1!:

lb 50 3b 20 3b 20 2b 2b 40 lb 10 2a 1b 10 L 2a 3b 3b 2b 2b 1b 1b 20 3b40 3b 4c 40---. 4a 2b 10 T T T T T T T T 41...-3a 2b is P P P P P I? P PP 4 42.... 3a 1b 3c O O O 43--.- 1a lb I 44-.-- 1a 3b 45-.--4u 3b 46-.--4a 2b 47----211 2b 48--..2a 1b 45 49-...1a 1b 4c I I I 50...-la3b1c K KK K K K K K K 51.-.-3a3b1c R R R R R R R R R 2!; P 2b M 111 L 1!] S 3!;3b 2b 2b 1b lcMMM 10 T T '1 3c S Pa P TABLE IV'Continued Signalstransmitted in dependence on programme P2 Pa P4 P ii"IIIIIIIIIIIPosition of switches At A B 0 P1 177--- 1a 3b 178 1a 2b 4c 179-.. 3a 2b4c 180 3a lb Pa P0 TABLE IV- Con'tinued Signals transmitted independence on programme P3 P4 P5 P0 Position of switches At A B 0 P1 P2660666 6066 0 868666 CC 0000 133552 2441 355224 41 1335 .Dbbbbb Db-Db .0bbbb '0 0b Obbb 133221 1332 2 1332%1 -13 90221 aaaaaa a CCCC CC C COCOCC CC 6666 C6 Ubbb .Db .Obbbbb Ub .Db Ob-Ubbbbb 1332 21 133221 1.3 3221133221 aaaa aa a aaaa aa a aaa 789% 00 OMOOOO W1 1m mnmwlmmww 9 91 11111.111 1.1 1.1 11111111 J I I I .0.D.D.D .Dbbbbb 3221 133221 Theexamples described make it clear that the invention provides for theseparation of the means effecting the time division switching programmefrom the means effecting the space division switching programme.

L 4c N bb DLU .D-Dbbbb .Db .Dbbb 32 211 133221 13 3221 It is seen thatas the result of this feature and through the selection:

(1) of the number of switches; (2) of the number of poles of each of theswitches;

(3) of the connection diagram,

by means of the device of the invention it is possible to providedifferent and variable switching programmes.

What is claimed is:

1. In a sequential switching device capable of storing and operatingaccording to a programme comprising a plurality of rotary switchesconnected to a common motive power input by kinematic chains comprisingunirform motion drive means and intermittent drive means, at least oneof the switches having contacts for electrical connection tocorresponding external signal sources and being capable according to thesaid programme of alternately moving to act as a scanning switch forexploring signals from said sources and remaining at rest connectionthrough one of the contacts; a timing switch, electrical connectionmeans connecting the timing switch in series with each rotary switch,the timing switch arranged to close the circuit through the scanningswitch during at least part of the time the scanning switch is at restand of maintaining a circuit open while the scanning switch is moving,kinematic chain means driving the timing switch from said common powerinput, and kinematic chain intermittent drive means driving each rotaryswitch from the timing switch so that it is successively at rest on onecontact and moving from one rest position to the next rest position,passing over a whole number of contacts determined by the kinematicchains connecting the scanning switch to the motive power input.

2. A device according to claim 1 comprising two scanning switches and acommon timing switch; electrical connection means connectingcorresponding contacts of the scanning switches together to form pairsfor connection to the said signal sources; and separate kinematic chaindrive means drivably connecting each scanning switch to the timingswitch, the various drive means cooperating so that one scanning switchis at rest and, in use, connecting with a signal source, while the otheris moving and is disconnected from the timing switch.

3. A device as claimed in claim 1 comprising at least one scanningswitch having rotary mounting means, a plurality of brushes mounted onthe said mounting means, adjacent brushes being separated by a distancecorresponding to a whole number of contacts, the brushes being so spacedthat, in each rest position of the scanning switch, the brushes will beconnected to circuits which are independent of one another; a furtherrotary switch having rotary mounting means and a plurality of brushesmounted thereon, the brushes being unequally spaced, adjacent pairs ofbrushes being separated by distances corresponding to a whole number ofcontacts; and connection means connecting the further rotary switch inseries between the timing switch and the scanning switch.

4. A device according to claim 1 wherein the said kinematic chainintermittent drive means is so arranged that there is a plurality ofpredetermined rest positions on the scanning switch, the scanning switchmoves over a plurality of contacts between adjacent rest positions, andthe scanning switch stops at least once at each of the said restpositions during the execution of the programme.

5. A device according to claim 1 wherein the said intermittent drivemeans comprises a mechanical delay line looped back on itself and havinga plurality of sequential elements, every second element being capableof storing a term of the programme so as to permit varying of anintermittent drive phase of the programme.

6. A device according to claim 11 comprising at least two switcheshaving different numbers of contacts, and a common intermittentkinematic drive chain arranged to drive the switches.

References Cited UNITED STATES PATENTS 2,568,906 9/1951 Williams 200382,57 9,983 12/ 1951 Thornton 200-38 FOREIGN PATENTS 999,510 7/ 1965Great Britain.

ROBERT K. SCHAEFER, Primary Examiner.

H. O. JONES, Assistant Examiner.

US. Cl. X.R. 307-41

